Alteration of the calcium content in inner hair cells of the cochlea of the guinea pig after acute noise trauma with and without application of the organic calcium channel blocker diltiazem
J. Maurer et al., Alteration of the calcium content in inner hair cells of the cochlea of the guinea pig after acute noise trauma with and without application of the organic calcium channel blocker diltiazem, ORL-J OTO R, 61(6), 1999, pp. 328-333
Citations number
33
Categorie Soggetti
Otolaryngology
Journal title
ORL-JOURNAL FOR OTO-RHINO-LARYNGOLOGY AND ITS RELATED SPECIALTIES
Calcium ions are known to be important to the process of signal transductio
n across the apical and basal sides of the inner hair cells. Calcium channe
l antagonists have been demonstrated by light microscopy to provide protect
ion against acoustic trauma. To evaluate the protective effect of calcium c
hannel blocker on the inner ear cells to noise exposure, the amount of the
histochemical reaction products formed in the cytoplasm of the inner hair c
ells of the guinea pig after application of pyroantimonate was measured by
an image processing system connected to an energy-filtering transmission el
ectron microscope (EFTEM). Compared to untreated control specimens (experim
ental animal group I) the amount of precipitable calcium had clearly increa
sed in the inner hair cells of noise-exposed cochleae 60 h after an acute n
oise trauma (group III). In addition, small electron-lucent areas could be
identified in the cytoplasm of the hair cells probably representing damage
to the cellular fine structure. When the calcium channel blocker diltiazem
was administered without any additional noise exposure the calcium content
was drastically reduced in the inner hair cells (group II), but when the an
tagonist was given before and after acute noise trauma (group IV), the calc
ium content in the inner hair cells was nearly compared to the amount deter
mined in the untreated group of animals. The role of diltiazem is discussed
in respect of tissue protection and to the maintenance of the calcium-depe
ndent physiological processes in the inner hair cells during signal transdu
ction.